Polymeric color formers



Patented June 27 1950 POLYMERIC COLOR FORMEBS piss Malcolm McQueen, Wilmington, Del, as- 1 signor to E. I. du Pont de Nem'ourl & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application February 18, 1948, Serial No. 9,330

This invention relates to new acetals of vinyl alcohol polymers and more particularly to acetals oi polyvinyl alcohol and m-benzoylacetamidobenzaldehydes.

An object of this invention is to provide new polymeric dye intermediates or color formers. A more specific object is to provide new polyvinyl acetal color formers. A further object is to provide such color formers which have improved col- 5 loid binding properties for light-sensitive silver halide grains. Still other objects will be apparent from the following description of the invention.

'The novel acetals of polyvinyl alcohol and m benzoylacetamidobenzaldehydes I which are provided by this invention may be represented by' the following structural formula 01 the c010 former units:

pared by reacting a vinyl alcohol polymer containing a large number of recurring intralinear groups with a m-benzoylacetamidobenzaldehyde or a lower acetal thereof with an alkanol of one to four carbon atoms or a 1,2- or a 1,3-alkanediol' or glycol of two to four carbon atoms in the presence of an acidic condensation catalyst. The.

in benzoylacetamidobenzaldehydes and their acetals just described may be prepared after the manner described in copending application Serial Number 667,126, filed May 3, 1946, now Patent No. 2,464,597, March 15, 1949, of which the present application is a continuation-in-part, by reacting ethyl benzoylacetate or a similar ester of a one to three carbon alkanol in an inert, high-boiling solvent, e. g., chlorobenzene or xylene, and a small amount of an alkaline catalyst, e. g., pyridine or aqueous KOH, with a lower acetal of a m-aminobenzaldehyde, e. g., the ethylene glycol acetal. The m-aminobenzaldehyde acetal is pref erably added after the components are heated to a temperature of 100 C. to 140 C. The ethyl alcohol released in the condensation reaction is distilled out 0! the mixture over a period of two 5 Claims. (01. 260-73) to four hours. After cooling, the reaction mixture is poured into water containing a sumcient amount of sodium hydroxide to dissolve the m-benzoylacetamidobenzaldehyde aceta'l. The water layer is separated, washed with a water-immiscible solvent, suchas ether, and saturated with carbon dioxide. The m-benzoylacetamidobenzaldehydeacetal separates as a solid or, in some cases, an oil. The material may be further purifled by repeated extractions or crystallization from suitable solvents.

The acetal interchange reaction, whereby the .novel acetals of this invention are prepared, may

be carried out as follows: A suspension of a .synthetic hydroxyl polymer having a plurality of recurring intralinear groups, e. 5.. polyvinyl alcohol, and a. m-benzoylacetamidobenzaldehyde or an acetal thereof with an alkalnol of one to four carbon atoms or a ,2- or 1,3-alkanediol of two to'four carbon atoms in ethylene glycol or other suitable solvent, e. g., ethanol or methanol, having dissolved therein a small portion of an acidic catalyst is heated with agitation at C. to 80 C. for a period of 0.5 to 25 hours and the resulting polyvinyl acetal is isolated. Isolation of the color-forming polymeric acetal is accomplishedby the addition of an ethylene glycol miscible solvent which is not a. solvent for the polymeric acetal, followed by filtration and, if desired, by washing with an ethylene glycol miscible solvent which is not a solvent for the polymeric acetal. 1 I

Ina practical procedure, a suspension of 15 partsof a polyvinyl alcohol and one to six parts of a m-benzoylacetamidobenzaldehyde or its ethylene glycol acetal in 100 parts of ethylene glycol containing one to two parts of phosphoric acid is heated with agitation at C. to C. for 0.5 to 5 hours. The reaction miximre is cooled to 40 C. to 50 C. and to 200 parts of methanol or acetone areadded. The resulting polyvinyl acetal color former is separated and slurried with methanol or acetone to free the polymer from the ethylene glycol and to remove traces of unreacted monomeric color former. In order to obtain a polyvinyl acetal whose color and solubility do not change on standing, it is desirable to treat the slurry of the polyvinyl acetal color former with a compound capable of neutralizing the acid catalyst. Suitable compounds for this process include alkoxides, alkali metal hydroxides, bicarbonates and carbonates; ammonia and its mono-, di-, and trialkyl substituted compounds, such as methylamine, dimethylamine, ethylamine, triethylamine, triethanolamine, etc. heterocyclic bases, such as quinoline, pyridine, etc. The quantity of neutralizing agent added to the suspension should to be suflicient to bring the pH to a value of about 6 to 8, preferably 7.5. The acid neutralizing compound may be dissolved in the solvent used during the dilution of the ethylene glycol reaction mixture, or may be added during any of the subsequent slurrying steps.

Other suitable acid catalysts for use in the acetalization of polyvinyl alcohol in ethylene glycol include acids, such as sulfuric acid, hydrochloric acid, and organic acids, such as chloroacetic acid, formic acid. methane sulfonic acid, para-toluenesulfonic acid, etc.

The use of ethylene glycol as a reaction medium is disclosed and claimed in Martin United States application Serial Number 722,961, filed January 18, 1947. Y

The invention will be further illustrated by the following examples. The parts are by weight.

Example 1 To a solution of 53 parts of m-benzoylacetamidobenzaldehyde ethylene glycol acetal (prepared asdescribed in United States application Serial Number 667,126, filed May 3, 1946), 1000 parts of ethanol, 250 parts of water, and parts of phosphoric acid was added 250 parts of finely divided polyvinyl alcohol (completely hydrolyzed polyvinyl acetate) having a solution viscosity of 18 to 24 centipoises in 4% aqueous solution at 20 C. The resulting slurry was stirred one hour at 80 C. and the reaction mixture was cooled to 60 C. and diluted with 1000 parts of acetone. After cooling to C., the polymeric acetal was collected in a filter and then slurried in methanol containing enough triethylamine to neutralize the residual acid catalyst. The polymeric acetal was again collected on a filter, slurried in fresh methanol, filtered, and finally slurried in two changes of acetone. After drying, the product weighed 260 parts. It was a colorless solid which dissolved in warm 20% aqueous ethanol. Colorimetric analysis showed that the product contained 6.5% by weight of the grouping.

NHC OCHaCO 06H] This corresponds to a polyvinyl acetal having 1.8% oi the hydroxyls of polyvinyl alcohol acetalized with the color-forming aldehyde.

Example 2 When 10.0 parts of o-sulfobenzaldehyde sodium salt were added tothe reaction mixture of Example 1 and the same procedure was followed as in Example 1, 265 parts of polymer were obtained. The polymer which was soluble in warm 10% aqueous ethanol contained 7.5% by weight of the color-forming unit of Example 1 and 4.5% by weight of the grouping [*kOH-CHr-CH-J sous.

based on the total weight of polymer. This corsulfobenzaldehyde sodium salt.

Example 3 A mixture of 15.9 parts of m-benzoylacetamidobenzaldehyde ethylene glycol acetal, 4.5 parts of o-sulfobenzaldehyde sodium salt, 500 parts of ethylene glycol, 7.5 parts of 85% phosphoric acid, and 75 parts of a finely divided polyvinyl alcohol (completely hydrolyzed polyvinyl acetate) having 4% aqueous solution viscosity of 18 to 24 centipoises at 20 C. was heated with stirring at 66 C. for 45 minutes. The reaction mixture was cooled to C. and 400 parts of methanol was added with stirring. The solid precipitate was then collected on a filter, neutralized with triethylamine, and then washed thoroughly with methanol and then with acetone. The yield of polyvinyl acetal was 79 parts. The polymer was a colorless solid and dissolved readily in warm 15% aqueous alcohol. Colorimetric analysis showed that the polymer contained 11% by weight of the color-former grouping shown under Example 1 and 6.7% of the solubilizing grouping shown under Example 2, based on the total weight of the polymer. This corresponds to a polyvinyl acetal having 3.4% of hydroxyls of polyvinyl alcohol acetalized with the color former and 3.0% of the hydroiwls acetalized with o,-sulfobenzaldehyde sodium salt.

Similar results are obtained by substituting equivalent amounts of m-(p-chlorobenzoylacetamido)benzaldehyde ethylene glycol acetal, m- (m-methoxybenzoylacetamido) benzaldehyde ethylene glycol acetal, m-(p-carbethoxybenzoylacetamido) -benzaldehyde ethylene glycol acetal, and m (p carboxybenzoylacetamido) benzaldehyde ethylene glycol acetal which can be prepared by the methods described in McQueen application Serial Number 667,126, filed May 3, 1946, now U. S. Patent 2,464,597, Likewise certain substituents may be included in thebenzaldehyde ring as, for example, in the following compounds: the polyvinyl acetals of 4-methyl-3-(benzoylacetamido) benzaldehyde, 4-methoxy-3- (benzoylacetamido) benzaldehyde.

The polyvinyl acetals of m-benzoylacetamidobenzaldehydes described above are useful as dispersing and protective colloid binding agents for light-sensitive silver salts in a gelatin-free multilayer color film. Color development of an exposed coated film with a primary aromatic colordeveloping agent, e. g., p-aminodiethylaniline gives a strong, brilliant yellow dye image.

When used as a yellow color former in a gelatin-free multilayer color film, polyvinyl acetals formed by color development are weak. When polymers having a higher degree of substitution are used, there is diiiiculty in obtaining good solutions and in redispersing the emulsion after washing.

In order to achieve more satisfactory water sensitivity for processing when coated on a suitable fllm base, the color-forming polyvinyl acetals can also contain a number of polymeric units wherein the hydrolyls oi the polyvinyl alcoholareaeetaliaedwithanaldehydoacimag ortho-suli phthaialdehydic acid. glyoxylicaoid.andthelikeortheiralkalimetal o-on a:

The preferred polyvinyl seems of this invention have the probable unit structure as follows in the proportions indicated:

) O-o-om-c- 3 3 1. Polyvinyl acetals which contain recurrin: A omdnon groups and groups of theiormula wherein X is taken from the group consisting of I hydrogen. chlorine, bromine, methyl. methoxy and COOC:H|.

2. Polyvinyl acetals which contain recurring roups and groups of the formula 3 o-on in; o-on on on I Q CINE O 0 OHi-O 0 Cent wherein a. equals 405 to 428 wherein 1 equals 3 to 8.3 wherein 2 equals 0 or 1 to 6.5.

This schematic representation shows only the relative amounts of the groups in the molecule. The color-former unit is not ily linked to the solubilizing unit but may be any place in the chain.

The synthetic hydroxyl polymers which can be used in the preparation of the color-forming polyvinyl acetals ot'this invention include hydroxyl polymers prepared by polymerizing a vinyl ester, e. g., vinyl acetate, vinyl propionate. vinyl benzoate, etc., alone or with minor proportions, l. e.,, 10% or less, of an unsaturated copolymerizable monomer, followed by partial or complete hydrolysis and, if desired, by :iurther reaction to introduce minor proportions of other modifying roups, e. g., acetal, ester, or ether groups. Such hydroxyl polymers have a linear chain consisting mainly of groups. Unmodified polyvinyl alcohol is the preferred hydroxyl polymer for forming the coloriorming polyvinyl acetals of this invention.

The m-benzoylacetamidoacetais of polyvinyl alcohol of this invention are superior to the macetacetamidoacetals of polyvinyl alcohol as binding agents for silver halides. The silver halide emulsions can be readily dissolved after noodling, whereas silver halide emulsions in maeetoacetamidoaoetals of polyvinyl alcohol show almost no tendency to redissolve aiter noodling. As many widely diiierent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to belimited except as defined by the appended claims.

What is claimed is:

3-. Polyvinyl acetals which contain recurring groups and from 5% to 12% by weight of the poly- 40 mer of groups of the formula wherein X is taken from the group consisting of hydrogen, chlorine, bromine, methyl, methoxy 50 and -CO0C2Hs.

4. Polyvinyl acetals which contain recurring groups and from 5% to 12% by weight of the polymer of groups of the formula H v H 0-611 c om-c-N oz on, so t t Make 3 J I 5. Polyvinyl acetals which contain recurring groups'and from 5% to 12% by weight of the polymer of groups of the formula fiumber REFERENCES CITED The following references ore of record in the me of this patent:

UNITED sums PATENTS Name Date Stusser Dec. 25, 1934 Schmid June 19, 1936 Borough Feb. 16, 1943 Dorough July 10, 1945 July 10, 1945 Jennings Apr. 2, 1946 

1. POLYVINYL ACETALS WHICH CONTAIN RECURRING 